Holographic Optical Element Coupler for High Power Fiber Laser Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for injecting high power laser light into optical fibers are complex, costly, and suffer from alignment sensitivity, lack of compactness, scalability, and insufficient coupling efficiency, often requiring mechanical etching or embedded micro-mirrors that weaken the fiber.
Innovation Solution
A holographic optical element (HOE) coupler, specifically a Bragg grating HOE, is used to couple high power laser light into optical fibers without mechanical alteration, utilizing a top and bottom HOE configuration with a sandwiched double-clad fiber, fabricated using interference fringes and commercially available high-efficiency photosensitive materials, allowing for high angular and spectral filtering selectivity and efficient light coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical etching or embedded micro-mirrors are used in the fiber cladding to couple laser light, then coupling efficiency is improved, but the mechanical integrity and strength of the optical fiber deteriorates
Solution Approach 1:
A holographic optical element (HOE) is introduced as an intermediary component between the laser array and the optical fiber. The HOE performs the light coupling function externally, eliminating the need for mechanical modifications to the fiber cladding. This mediator approach achieves high coupling efficiency while preserving the fiber's mechanical integrity.
Solution Approach 2:
The patent replaces mechanical coupling methods (etching, embedded mirrors) with a holographic optical element that uses optical interference patterns to achieve light coupling. This substitution eliminates mechanical stress on the fiber while maintaining high coupling efficiency through the HOE's diffractive optical structure.
2Power
If complex laser pumping schemes are employed to achieve high power injection, then pumping power capability is improved, but device complexity increases
Solution Approach 1:
The holographic optical element serves multiple functions simultaneously: it couples light from multiple laser diodes, performs spatial filtering, and directs light into the fiber core. This multi-functionality in a single component reduces overall device complexity while maintaining high power pumping capability.
Solution Approach 2:
The patent merges the functions of light coupling, spatial filtering, and beam shaping into a single holographic optical element. By combining these functions that would otherwise require separate components, the system achieves high power injection capability with reduced structural complexity.
3Ease of operation
If traditional coupling methods are used, then alignment tolerance is improved, but coupling efficiency deteriorates
Solution Approach 1:
The holographic optical element is designed with specific grating parameters and spatial frequencies that optimize both coupling efficiency and alignment tolerance. By carefully controlling the HOE's optical parameters during fabrication, the system achieves high efficiency coupling while maintaining robustness against alignment variations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The HOE coupler provides high coupling efficiency (>80%) with minimal perturbation of the fiber structure, is insensitive to misalignment, and is cost-effective, making it suitable for high-power laser array applications with universal compatibility for various inner cladding shapes and designs.
Implementation Method 1
interference fringes are created using an array of stepped micro lenses for generating an array of beams interfered with by a referenced beam
Implementation Method 2
The HOE coupler is preferably a Bragg grating holographic optical coupler
Data Source
AI summary
A transmissive holographic optical element including a chirped grating is used to inject light by side firing laser light from a an array of laser diodes into an optical fiber with a reflective HOE reflecting the injected laser light through and along the optical fiber with the transmissive holographic optical element HOE and reflective HOE sandwiching a portion of an optical fiber for increased laser side firing pumping efficiency in optical fibers.